Help me give my evil henchman a personality and purpose in life.

I have a decent amount of antagonist/villains. I want them each to be a distinct and have a depth of personality. The main problem is at the bottom, but I would welcome suggestions for any. Once I wrote them out, they seem very stereotypical; but when I was creating them, they felt like the natural result of their background.

Evil stepmother – Impulsive and emotional. Creates her own reality and forces others to affirm it or face the consequences. Lives in the moment. Unable to foresee long-term consequences. Married into highest social position in country but originally came from a criminal family that lived on the fringe of high society.

Overindulgent lord – hedonist. Allows wife control as long as she facilitates his lifestyle. Can be generous as long as his generosity does not interfere with his comfort. Will abandon any person or project at first sign of discomfort.

Big bad – Bitter abandoned child ready for revenge. Charismatic and extremely successful. Systematic in his plot to destroy the group that wronged him.

Mad scientist – single-mindedly pursuing redemption for his family. Brilliant in the lab but clueless with people. Dedicated. Curious. Optimistic. Outcast of high society.

Evil stepmother‘s henchmen – here’s where I’m lost.

This is what I have so far… Evil stepmother’s cousin. Former palace guard who is dismissed four immoral conduct. He must be cruel enough to kidnap and possibly kill a child. He should feel threatening to a young teen.

I have two problems. First, I can’t grasp a personality for him. How can I make him the scary muscle but not a cardboard cut out character. Second, I can’t figure out why he would work for the evil stepmother for 10 years as her evil henchman. He disposed of her step child for her 10 years ago and can prove it. Why doesn’t he blackmail her for his income and live a life of leisure?

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